Stabilized parasiticidal compositions



Patented Mar. 29, 1938 PATENT OFFICE STABILIZED PARASITIOIDAL COMPOSI- TIONS Paul L. Salzberg, Wilmington, Del., assignor, by

mesne assignments, to E. I. du Pont de Nemours & Company, Wilmington, Del a corporation of Delaware No Drawing.

Application January 6, 1936, Serial N0. 57,785

9' Claims. (01. 167-30) The present invention relates to parasiticidal compositions which contain as an active toxic ingredient a thio-diarylamine and a substance which counteracts the atmospheric inactivation of said toxic ingredient.

Thio-diarylamines have lately been shown to have exceedingly. valuable toxic properties towards lower forms of life, especially towards insects, and they have been shown to be very eificient stomach poisons for various insect pests. Parasiticidal compositions which, for their efliciency,- depend 'upon the toxicity of mm- I diarylamines contained therein suifer, however,

from the serious drawback that their toxicity and .efliciency greatly diminish when the agents are exposed to atmospheric conditions.

I have found that this atmospheric inactivation can be decreased or nearly prevented if the stance or solution, is exposed to the atmosphere,

its color turns gradually green. I have also -found that this discoloration is observed on impure, technical thio-diphenylamines which are of yellowish or brownish-color, in all instances the color changes to one .of shorter wave length.

This change in the thio-diphenylamine can be greatly accelerated for instance by traces of ferric chloride added, for instance, to an acetone solution of thio-diphenylamine I I have observed that the changeof the thiodiphenylamine from yellow toward green greatly afiects its toxicity towards lower forms 01'. life,

. such as insects, in that a greenish thio-diphenylamine has considerably less activity as-a parasiticide than the original yellow productvVhich,

on exposure to theatmosphere, was discolored.

I have found that when this discoloration is inhibited, the activity of'the thio-diarylamlnes is preserved. I have further made the surprising discovery that if the green discoloration is-.-pre.-

vented entirely, the initial toxicity of 'thiodiphenylamine is materially reduced. -'It appears as if the toxicity is at least partly due to the ability of thio diphenylamine t0 Ox d'izc," but on the other hand the rate of oxidation must be controlled in order tov render the product active over a s'ufficiently long period oitime. It will be recognized, therefore, that the problem is, not one of simply preventing atmospheric decbmposition but rather the more complex problem of. controlling the rate of decomposition. l

Suitable inhibition of discoloration and inactivation of the thio-diarylamines is produced by chemical substances of various constitutions. Some of such substances are known to act as anti-oxidants in the preservation of rubber, others act as anti-summing agents tor petroleum distillates, but their activity in the present invention does not always run parallel with their activities insuch other fields.

Some of the outstanding inactivation inhibitors belong to two types of chemical substances, but these groups are not all embracing as not every member of these groups will be found sufiiciently active to be of practical interest, and on the other hand, active inhibitors, such as hydrazine or phenylhydrazine, have been found diphenylamine and expose the mixture to the I v atmosphere." Thio-diphenylamine, which is originally of a yellowish color, appears somewhat green on the surface of-the sample in about two weeks time' and is very green after two months exposure under winter conditions. It turns green very muclr more rapidly in direct summer sunlight. I v

In a greatly accelerated discolorationtest I use an acetone solution of thio-diphenylamine and, add to such a solution a few drops of ferldc chloride solution. In the absence of a substance '01.

such character, and in such amount as to inhibit inactivation of the thio-diphen'ylamine, the acetone solution turns immediately green or other shade of short wavefingth, whereas the solution maintains substantially itsscolor, or simply turns yellowish or brownish, or changes to colors of longer wave length than the original solution, if

the solution contains a suificient amount of substance which will inhibit inactivation.

Substances which I found to prevent discoloration of thio-diphenylamine to colors of shorter wave length have, for instance, been found as tained from phenyl-alpha-naphthyl amine which presumably has the formula II N CQHI CioHs follows: or from phenyl-beta-naphthylamine,

C oncentrzztiton E T t 1: respec o xposure as exposure substance thio-diphenyltime appearance amine Per cent Thio-diphenylamine alone 2 weeks--. Green on surface Hydroquinone-. 1 6 months. '81. red on surface Hydroquinone. 0. 5 456 months Red on surface Hydroquinone- 2 do Do. Bete naphthol 5 2% months Very little change Mono-lauryl ether of hydroquinone 1 do S1. brown on surface gl-[Hydroxyphenyl-morpholine- 1 .-do Brown on sur ono-benzyl-p-amiuo phenol- 1 d Do. Diphenyl-guanidine 1 do. Red on surface Lauryl cetechol 1 .do Brown on surface Tannic acid 1 do Do.

In the above described accelerated ferric chloride discoloration tests I found, for instance the same substances quite effective for prevention of color change in thio-diphenylami'ne solutions towards the blue end of the spectrum.

The exposure test and the accelerated ferric chloride test give entirely parallel results, except in'some cases with phenolic inhibitors where the phenols or naphthols may react with the ferric chloride to produce deeply colored compounds, but

in the case of amines and other non-phenolic materials, I found that the accelerated-ferric chlo- ,ride test gives a safe guide for predicting the effect of a certain compound to inhibit the inactivation of the parasiticidal value of a thio-diarylamine.

The efiect of these discoloration inhibitors of prolonging the potency of thio-diarylamine parasiticides is made use of by intimately mixing these substances in small amounts, for instance, from 1 to,10% with the parasiticidal compositions, as for instance, the aqueous sprays containing the usual spreading and wetting agents or by incorporating into the dry dusts the thiodiarylamine, the requisite amount of inhibitor and the usual diluents such as talc, silica powders, etc. and then applying such compositions in a conventional manner to the plants to be protected from parasiticidal attacks. The thiodiarylamine insecticides which are amenable to the effect of my novel inactivation inhibitors are water insoluble compounds of the general formula in which R and R are aromatic nuclei and R is hydrogen.

The proto type of these compounds is thicdiphenylamine, which is produced, for instance, by heating diphenylamine with sulfur in the presence of a catalyst, such as aluminum choride, ferric chloride, iodine, etc.

Other members of the novel group of insecticides, according to my invention, are the thio compounds obtained by the action of sulfur upon diarylamines such as, for instance, those obdi-alpha-naphthylamine,

di-beta-naphthylamine,

di-biphenylamine,

N, N-diphenyl-p-phenylenecliamine,

N, N-di-alpha-naphthyl-pa'ra phenylene-diamine,

N, N di biphenyl q metaphenylene-diamine,

N, N-di-phenyl-metaphenylene-diamine,

N, N-di-phenyl-benzidine,

p, p'-di- (phenyl-amino) di-phenylamine.

The mm derivatives obtained from these diarylamines are all characterized by containing the heterocyclic nucleus in which R and R are aromatic nuclei in each of which two adjacent carbon atoms take part in forming the heterocyclic carbon-nitrogen-sulfur ring, and R 1 is hydrogen.

Some of the hydrogen atoms normally attached to R and R may be substituted, or replaced by alkyl, cyclo-alkyl, aryl, hetero-cyclic nuclei, or halogen, nitro, amino, alkoxy or aryloxy groups.

Among the novel inactivation inhibitors of my invention, I prefer to use those which are insoluble or diflicultly soluble in water.

The inhibitor may be ground together with the thio-diarylamine whereby an intimate mixture of the two is obtained. I also may incorporate the inhibitor into the parasiticide by means of a common solventfor the. two with subsequent evaporation of the solvent. Furthermore, and particularly in the case of thio-diphenylamine I might add the inhibitor, if stable under such conditions, to the molten thio-diphenylamine at the conclusion of the sulfurization of diphenylamine.

The substances which were found to inhibit the discoloration of thio-diphenylamine were also found to inhibit the inactivation of the thiodiarylamines when exposed to atmospheric conditions, for instance, when in contact with air under such conditions as exist when the parasiticidal compositions are applied to plants, etc.

tive parasiticidal ingredient; a thio-diarylamine and, as the stabilizer, from about 1 to of an antioxidant which, when present in an acetone solution of thio-diphenylamine, prevents the color of said solution from changing to a shorter wave length on addition of ferric chloride thereto.

3. A parasiticidal composition stabilized against in such an amount as to retard atmospheric inactivation oithio-diarylamine.

2. A parasiticidal composition, stabilized against atmospheric inactivation, comprising. as the acammo, atmospheric inactivation comprising as the ac- 7 Composition Outdoor Mexican bean tive parasiticidal ingredient a tide-diphenylamine 10 ggg g g g? and a phenolic compound which has the property of inhibiting the discoloration oi thio-diphenyllphmmomphenylamm None 100 amine toward the short wave length of the Pure thin-diphenylamine 6weeks 40 spectrum when exposed to atmospheric condig ggz hydm' tions in admixture with said substance, said Pure thid-diphenylarnine-i-Wi, hydro- 0 weeks. phenolic compound being present in such an amount as to retard atmospheric inactivation of a thio-diphenylamine.

It is seen from this that while pure thio- 4. Aparasiticidal composition, stabilized against diphenylamine lost 60% of its activity after six atmospheric inactivation, comprising, as the acweeks atmospheric exposure, the addition thereto tive parasiticidal ingredient, a thio-diar'ylamine of 1% hydroquinone reduced this loss of activity and, as the stabilizer, from about 1 to 10% of a to about 22%. phenolic compound which, when present in an In another set of tests apples were sprayed with acetone solution of thio-diphenylamine, prevents a parasiticidal composition at the rate of three the color of said solution from changing toa 26 pounds per 100 gallons, they were then exposed shorter wavelength on addition of ferric chloride to sunlight and air for flve days and infected with thereto. g

codling moth. Apples freshly sprayed with the 5. An-insecticidal composition stabilized against spray were immediately infected and the results atmospheric inactivation comprising thio-diare tabulated below: phenylar'nine and -'beta-naphthol in such an 80 Per cent control nga? Percent im- Composition gg fi m g flininigal 852213; I" tti iiisiti an? J activity) P 88 53 40 hen..." "9. t

79 so so neit iifpiiitizz: titi The term antioxidant as used in the apamount as to retard atmospheric inactivation of pended claims is notintended to berestricted to thio-diphenylamine.

substances which act as antioxidants in the 6. Aninsecticidal composition stabilized against preservation oi rubber, but is to be interpreted acatmospheric inactivation comprising thio-dlcording to its broader significance as comprehendphenylamine and hydroquinone in such an ing in addition thereto not only substances which amount as to retard atmospheric inactivation of act as anti-gumming agents for petroleum thio-diphenylamine'. distillates but also substances which, inthe broad '7. The composition of claim 1 in which said sense oi the term antioxidant, would be so antioxidant is an aromatic amine. classified by thoseskilled in the various chemical 8. Aparasiticidai composition, stabilized against arts. atmospheric inactivation, comprising, as the ac- I claim: tive parasiticidal ingredient, a thio-diarylamine 1. A parasiticidal composition stabilized against and, as the stabilizer, from about 1 to 10% oi an atmospheric inactivation comprising as the acaromatic amine which, when present in an tive parasiticidal. ingredient a thio-diarylamine acetone solution of two-diphenylamine, prevents and an antioxidant which inhibits the discolorathe color of said solution from changing to a tion of ting-diphenylamine toward the short wave shorter wave length on addition of ferric chloride length of the spectrum when ferric chloride is thereto. added in a small amount to an acetone solution of 9. An insecticidal composition stabilized against thio-diphenylamlne containing a small amount atmospheric inactivation comprising thio-diof said antioxidant, said antioxidant being present phenylamine and diphenyl guanidine in such an amount as to retard atmospheric inactivation of thio-diphenylamine. I

PAUL L. SALZBERG. 

